High Ice Water Content (HIWC) can be ingested into aircraft engines as small ice crystals. When ice crystals hit warm aircraft engines, they start to melt and evaporate, cooling the engine core surfaces to temperatures below freezing. The cooling engine causes the melted ice crystal water to refreeze, and ice accumulates inside the engine core. Ice in this location may cause temporary power loss or engine blade damage.
Ice crystal encounters are difficult to avoid because of their poor radar reflectivity characteristics. To assist operators that utilize engines impacted by HIWC, DTN has developed a forecast product that highlights where the potential for engine icing is likely.
Overview
| Geographical Domain | Forecast Horizon | Forecast Time-Step | Forecast Resolution | Update Frequency | Flight Levels | Forecast Value |
|---|---|---|---|---|---|---|
|
North America |
18 hours |
1 hour |
13km output at 13km grids |
Every hour |
11 unique levels between FL300 and FL410 |
Light, Moderate, Severe |
|
Global (80N-80S) |
36 hours |
13km, output at 25km grids |
Every 6 hours |
Accessing the High Ice Water Content Forecast
DTN’s HIWC product is available within our Data Delivery Services and Flight Route Alerting API.
Flight Route Alerting
To access real-time alerts of High Ice Water Content within DTN’s Flight Route Alerting API, you will need to call the new High Ice Water Content alarm type.
| Alarm Type | Property | Example Value | Value Type |
|---|---|---|---|
|
HighIceWaterContent |
Category |
Severe |
String-enumeration |
Data – Web Mapping Service
| Content | “Get Map” Layer Name | Description | Dimensions |
|---|---|---|---|
|
High Ice Water Content |
NA_HIGH_ICE_WATER |
Forecast of High Ice Water Content potential over North America. |
Flight Level (dim_flight_level) |
|
High Ice Water Content |
GBL_HIGH_ICE_WATER |
Forecast of Worldwide High Ice Water Content potential. |
Data – GRIB Format
File Bundle Naming Convention
The individual HIWC GRIB2 files are tar’ed together with the other DTN Flight Hazard GRIB data and then compressed by standard zip utility application for distribution.
The naming convention of the tar’ed, zip file is:
Filename definition: <CCCC>_<MMM>2_<RR>_<MMDD>_<FF>.TGZ
Where:
-
CCCC= Issuing office identifier (DTN0)
-
MMM = Model (GFS or RAP)
-
RR= Resolution (02 for GFS / 13 for RAP)
-
MMDD = month and day of model run
-
FF= Forecast hour (06, 09, 12,…36)
File Naming Convention
The files use a WMO Header file naming convention:
Filename definition: <M><P><G><I><LL>
Where:
-
M= Model Code
-
P = Parameter Code
-
G = Grid Code
-
I = Forecast Interval Code
-
LL = Level Code
| Model Code (M) | Parameter Code (P) | Grid Code (G) | Forecase Interval Code (I) | Level Code (LL) | |||
|---|---|---|---|---|---|---|---|
| Code | Code | Code | Description | Code | Description | Code | Flight Level |
|
H (Always) |
i (Always) |
D |
North America |
A |
1 hour forecast |
18 |
FL410 |
|
|
|
Y |
Global |
B |
2 hour forecast |
19 |
FL400 |
|
|
|
C |
3 hour forecast |
20 |
FL390 |
||
|
…. |
…. |
21 |
FL380 |
||||
|
Z |
25 hour forecast |
D1 |
FL370 |
||||
|
a |
26 hour forecast |
22 |
FL360 |
||||
|
b |
27 hour forecast |
23 |
FL350 |
||||
|
…. |
…. |
25 |
FL340 |
||||
|
k |
36 hour forecast |
26 |
FL330 |
||||
|
|
|
27 |
FL320 |
||||
|
30 |
FL300 |
||||||
Data – Shapefile Format
DTN can also provide data delivery of the HIWC Forecast in Shapefile format.
File Naming Convention
Shapefile Name: FH_(fm)G(I)HW(fh)(md)(mh).shp
Where :
-
(fm) = Forecast model (NX – North America and WP – Global)
-
(I) = Flight level code (1 character, see code listing below)
-
(fh) – Forecast hour code (2 digits) – hourly from 01-18, WP – hourly from 03-36
-
(md) = model run day (GMT – 2 digits)
-
(mh) = model run hour (GMT – 2 digits)
| Forecast Model Domain (fm) | Flight Level Code (I) | Forecast Hour Code (fh) | Model Run Day (md) | Model Run Hour (mh) | |||
|---|---|---|---|---|---|---|---|
| Code | Description | Code | Flight Level | Code | Description | Code | Code |
|
NX |
North America |
9 |
FL410 |
01 |
1 hour forecast |
GMT (2 digits) |
GMT (2 digits) |
|
WP |
Global |
O |
FL400 |
02 |
2 hour forecast |
|
|
|
|
|
J |
FL390 |
03 |
3 hour forecast |
||
|
N |
FL380 |
…. |
…. |
||||
|
7 |
FL370 |
36 |
36 hour forecast |
||||
|
M |
FL360 |
|
|
||||
|
T |
FL350 |
||||||
|
I |
FL340 |
||||||
|
V |
FL330 |
||||||
|
6 |
FL320 |
||||||
|
H |
FL300 |
||||||